Apparatus for the reception and transmission of wave energy in space



June 21, 1932. H. HECHT ET AL APPARATUS FOR THE RECEPTION ANDTRANSMISSION OF WAVE ENERGY IN SPACE Filed Nov. 30, 1929 3 Sheets-Shet 1June 21, 1932. H. HECHT ET AL 1,863,716

APPARATUS FOR THE RECEPTION AND TRANSMISSION OF WAVE ENERGY IN SPACEFiled Nov. 30, 1929 3 Sheets-Sheet 2 HM Hm, WM @W June 21, 1932. H.HECHT ET AL APPARATUS FOR THE RECEPTION AND TRANSMISSION OF WAVE ENERGYIN SPACE 3 Sheets-Sheet 3 w 0 1 m w A /M \u h 0% a I M \\J/ W m \\X i oO Patented June 21, 1932 UNITED STATES PATENT OFFICE HEINRIC H HECHT ANDWILHELM RUDOLPH, OF KIEL, GERMANY, ASSIGNORS TO ELECTROACUSTICGESE'LLSCHAFT MIT BESCHRANKTER HAIETUNG, OF KIEL, GER- MANY, A FIRM FGERMANY APPARATUS FOR THE RECEPTION AND TRANSMISSION OF WAVE ENERGY INSPACE Application filed November 30, 1929,5eria1 No. 410,763, and inGermany lJecember 6, 1928.

The invention relates to arrangements of a type by which, by means of aplurality of oscillators distributed over a surface, wave energy, forinstance, sound, is directionally emitted or received in a plane inwhich this surface lies. Arrangements dealing with this particularsubject matter are disclosed for instance in the U. S. applicationSerial No. 331,286, filed January 9, 1929, by the present applicantHecht, and the co-inventor Heinrich Stenzel. Arrangements of this typehave. a characteristic which makes possible not only the determinationof direction or directional transmission in one plane as described inaforesaid application, but also in space. This applies both to anorderly and an irregular distribution of oscillators, particularly toarrangements in circles, and in simple and combined groups. According tothe present invention, such oscillators can be used for directionaltransmission or reception of wave energy in space by connecting them, inthe case of a fixed arrangement in space, with a compensator whichallows of swinging the directional vector in s ace.

A most advantageous arrangement 0 this kind is characterized by thefeature that it is composed of several individual groups fixed in spaceto form a complete structure, the different individual groups havingtheir zones of maximum directional and transmitting sharpnessrespectively in different directions in space, and the swinging of thedirectional beam or the determination of the direction of the incidentenergy is carried out by means of so-called compensators. The individualgroups may, in this case, be manipulated either by one or more observersseparately or at the same time.

Constructional examples of the invention are given in the drawings inwhich Fig. 1 shows diagrammatically the directive range of a circulargroup of oscillators,

Fig. 2 an arrangement of oscillators con sisting of three separatecircular groups, arranged in three planes at right angles to oneanother,

Fig. 3 two groups of oscillators consisting of a horizontal circulargroup and a ver tical linear group,

Fig. 3" shows diagran'nnatically the directive range of a verticallinear group of oscillators,

Fig. 4 shows an oscillator arrangement consisting of three linear groupsarranged in space at right angles to one another,

Fig. 5 shows the manner of ascertaining the space bearing with the twolinear horizontal groups shown in Fig. 4, 7

Figs. (3 and 6 show plotting devices to taking bearings with anarrangement according to the principle implied in Figs. 4 and 5,

Fig. 6" shows the circuit arrangements of the compensator used in anoscillator arrangement according to Figs. l, 5 and 6, and

Fig. 7 shows another form of plotting device with an oscillatorarrangement and principle according to Figs. 4: and 5.

Referring first to Fig. 2, which shows diagrammatically the arrangementfor space direction finding, three groups 1, 2, 3 of oscillators(transmitters or receivers) arranged in circles of suitable diameter areprovided at the station, which circles have a common center, theircircular planes cut-ting one another at right angles. The locations ofthe oscillators on the circles are represented by small circles. Theoscillators are distributed on the circles in equal number and atuniform distances apart. For the transmission or reception of energy ina certain direction, the horizontal characteristic of each circle isused, which yields a main maximum in the plane of this circle To explainfirst more fully the basis on which the observation with an arrangementsuch as in Fig. 2 rests, reference is made to the diagrammaticillustration Fig. 1. This diagram shows in perspective view only theazimuth circle with the oscillators distributed over its periphery asindicated by small circles. The plane of this circle is assumed toextend atright angles to the paper. This arrangement by itself is insubstance similar to that described in the aforementioned application,Serial No. 331.286. The individual devices while located on a circle,say of ten foot diameter, represent, for instance in case of signalreception from a far distant point, of course only a point denoted inFig. 1 by P as the center of the circle in whlch the arriving beamscenter. Let us assume first a signal arriving from a distant point 0,which is located in the plane of the clrcle. The receiving device 6which the beam 02 emanatlng from 6 passes, receives the sound at amaximum, while the intensity in the adjacent other devices decreases toa degree, the more, the further they are away on the circle from devicee Let us now consider only the device e through which beam n is drawn.The signal intensity in this device decreases on eitherside of beam linem, the further the distant origin 0 of the sound is angularly removed toeither side of beam in in the plane of circle 1. These signal strengths,if plotted result in a. curve indicated by 71, and the plane of which islocated in the plane of circle 1.

If now the distant sound source should move from the point 0 at rightangles to the circle plane, namely in the plane of the paper, to thepoint 0 so that the new sound beam 12 includes an angle of 45 with m.The maximum sound intensity of the signal received by device 6 is thensmaller than the maximum received from the same signal source when at 0This is indicated by theshorter length of beam m. If the source shouldmove from O to either side of beam 72 but at right angles to the paper,an intensity curve similar to f can be plotted as is shown at f Theplane of this curve is also at right angles to the paper and passesthrough n which shows its apex. Thus a number of curves may be plottedbet-ween f and f for sound sources at different angular elevationsrelatively to the plane of circle 1 which curves are indicated in dottedlines. If this group of curves were surrounded by an envelope, its formmight be likened to a flattened fig, which is transversely bisected bythe plane of circle 1, and whose stem is theoretically in the center ofthe circle. For each of the devices such as 6 on the circle, a similarenvelope exists. The group of curves shown in Fig. 1 is called thehorizontal characteristic of the circular group of devices. With such ahorizontal group of devices alone, when arranged in a horizontal circle1 as shown in Fig. 1, it is still possible to sufficiently exactlydetermine the azimuth of a sound source, provided the angular elevationof the source above the circle is not beyond 45, at which elevation (seebeam 12 the sub-maximum of the characteristic is still about of the mainmaximum (see beam 724 Similar characteristics may be plotted for thegroups of devices arranged in the circles 2 and 3 of Fig. 2.

Now in locating for instance a sound source in space by observing thesound maxima with on the circle throu h the three groups of devices, onewould proceed, according to the location of the source the source hasthe smallest angular elevations.

For instance, as shown in Fig. 2, in case the source is located in thedirection a, the groups in circles 2 and 3 would be selected forobservation, for direction 6, groups 1 and 3, and for direction 0,groups 1 and 2 would be selected. For the direction a, the devices ofgroup 1 would give no maximum at all, because all devices of this groupare symmetrically located to the source in that direction. This isrespectively true with regard to direction 0 and group 3, and directionI) and group 2.

g If now the sound source should come from the direction d, which is infront of plane 3, above plane 1, and to the right of plane 2, and if weassume first that the spherical angles a, ,6, y, are equal, observationscan be made with any pair of circular groups 12, 1-3, or 2-3 to find theexact direction of beam d. If beam d should shift toward plane 1,observations must certainly be made with group 1, and in addition may bemade either with 2 or 3. If beam cl should shift toward plane 2 andtoward 3, the best observations can be made with group 2 and 3. If dmoves down and more to the front, groups 1 and 2 should be used and soforth.

In general the rule prevails that the best results are obtained alwaywith thegroups,

whose planes have the smallest angular inclination to the sound beam.

The observer would proceed for instance as follows: He always observeswith only one group (in one plane) at a time, and notes the angle inthat plane at which the maximum is observed. If he takes for instancegroup 1 as a basis, he may take the angle found as the azimuth angle, inwhich case the observations with the two other groups serve fordetermining the exact elevation of the source. Of these two latterobservations the one with the greater maximum would be the more exactobservation, because it implies the smaller relative angle. If the twomaxima are equal, it is immaterial which of the two elevation values hetakes for his calculations.

The described arrangement has the advantage that only a standardcircular compensator is necessary which can be used for each of thecircular groups of oscillators.

A further simplified arrangement is shown in Fig. 3. It consists of onlytwo groups, namely a horizontal circular group 1 (azimuth circle) and avertical linear group 4. These groups give together a very usefuldetermination of bearings within a zone of 45 angular elevation abovethe horizontal plane throughout the whole circle. For the azimuthcircle, an explanation has already been given above with reference toFig. 1.

"i sphere N aroun The linear cup 4 to be used for the determination of lieight also has its maximum accuracy in a zone which lies within anelevation of about i with respect to a plane at right angles to it. Theaccuracy of taking bearings in this arrangement, therefore becomes thesmaller the nearer the object of which the bearings are to be taken liesto the point vertically above circular group 1. v

In this case the horizontal characteristic of the circular grou 1 is thesame as in Fig. l and has been omitted in Fig. 3 for clearness sake."Only the characteristic of the vertical straight line oscillator group4 is shown in Fig. 3 for the three elevations a, b, c. The respectiveindividual closed curves are shown in dash lines in perspective i. e.their planes should be assumed to extent at right angles to the paper.They are shown for observation above the horizontal plane and fordifi'erent'elevations in one azimuth angle plane only. Thus if theobject sought is located in the direction a (left or right) i. e. if theelevation is zero, a symmetrical curve with a very sharp maximum isobtained; at the. elevation b a slightly unsymmetrical curve with a lesssharp maximum; and at the elevation 0, far over 45, the unsymmetry andbroadness of the maximum are increased to such an extent, thatobservations at this elevation are of no value for practical purposes.

The observer would in that case proceed as follows: He first ascertainsthe. azimuth angle, using the circular group 1 according to Fig. 1. Thenhe uses the vertical row 4 of oscillators to ascertain the elevation.When taking bearings from the ground, the observer is of course onlyinterested in the upper half shown in Fig. 3, because in that case theobservation is single valued.

For this arrangement, of course, two different compensators arenecessary, one circular compensator for the azimuth circle and onelinear compensator.

A particularly advantageous arrangement for taking bearings or fortransmission in space is shown in Figs. 4 and 5. It consists of twocrossed linear groups of oscillators 5 and 6. The devices are againrepresented by small circles. Fig. 5 serves for understanding how thedetermination of bearings is accomplished here. In this figure the twoheavy lines 5 and 6 represent the two crossed horizontal linear groups 5and 6 of Fig. 4. A straight line group is, as is well known,characterized by the feature that the geometric place for all soundsources, which give a maximum at the same adjustment of the compensator,can be considered as the base circle of a cone whose apex is located inthe centre M of the linear and whose plane is parallel to the group.This circle can be considered further as bein cut by this cone out of ad M of any assumed radius.

Thus it is clear that, for the base 5, the directions of all sources Sof the aforementioned maxima must be located on the cone base circle 8,two generatrix lines of which are indicated by the dash lines Mg and Mh.For the base 6 the directions of all sources S of the aforementionedcharacter would li e on the cone base circle 9 with the two generatrixdash lines Mi and Mk. Part of the base circle 8, shown in full line, isdirectly visible, the remainder, shown as a dash line, lies behind. Thebase circle 9, shown in dot-dash lines is entirely on the rear portionofthe sphere. a

The two points of intersection of these cone base circles indicate .the'exact location of the source in space. lVith the observer in free space,this determination of bearings would be equivocal since the two conebase circles have two points of intersection S and 8,. If. however, thedetermination of bearings or the transmission is done from the ground, Srepresents the mirror image of S lying be low the ground and is omittedfor the measurement, so that the latter clearly yields the single valueddirectional ray MS which, geometrically, represents the line ofintersection between the two cone surfaces having the bases 8 and 9, andforms the only sound vector, common to both base circles and conesurfaces.

If for direction finding only two crossed linear oscillator groups 5 and6, Figs. 4 and 5, are used, which are located in a horizontal plane, thedirection determination is most exact in the neighborhood of the zenith,and

least exact or broadest in horizontal direction. This disadvantage canbe overcome by using a third vertical line of oscillators, such as shownat 7 in Fig. 4, which would be used by the observer as described withreference to Fig. 3.

For measuring purposes with two base lines such as 5 and 6 in Figs. 4and 5, two linear compensators are used, which, however, are notactuated one after another or by different observers but, better, at thesame time by the same observer. They are both connected to the sametelephone (or other indicating instrument) in which this observerperceives the indications of the maximum. He has nothing else to dothen, by varying the two compensators, to adjust the absolute maximum,for it is clear that the latter, in the example illustrated in Fig. 5.can only occur at the adjustment corresponding to the two cone circlesand that a deviation from this adjustment to the one or the other basemust necessarily lead to a reduction of the heard or indicated waveenergy.

Since both linear groups yield their greatest accuracy when the objectwhose bearings are to be taken lies near its vertical central plane(median plane), then it is evident that the accuracy of determiningbearings here increases toward the apex where it attains its with which,after the above described adjustment, a more accurate redetermination ofthe height is carried out with the two'compensators of the horizontalgroup. No spe cial compensation is necessary therefor but,

with the same number and distribution of;

receivers, one of the two compensators of the horizontal groups can "beused for the vertical group.

Concerning working out the measurements, it is clear that, with allthose group combinations where the measurement of azimuth and elevationis done by separate measuring operations, the two values on theparticular compensators are directly and individually read off onsuitable scales. In arrangements of the type where both values areascertained by a measuring operation and which are explained by aid ofFigs. 4 and 5, it appears desirable. also to directly indicate bothvalues at the same time. A fundamental group of possibilities ofindicatio ns can be deduced from the consideration of Fig. 5 if it isimagined that a visible guiding element (pointer, light beam or thelike) or the two cone base circles are moved on a hemisphere arrangedover the bases 5 and 6 and are divided into meridians 5, 6 as polaraxes, depending upon the compensators adjustment. Instead, it is alsopossible to conceive projec tions of the light beam or of the cone basecircles moving on the horizontal plane on just such a projection of thehemisphere division. Of course, a division of the hemisphere intolongitudinal and latitudinal circles or into greatest sphere circles ora projection of such a division on a plane can also be used.

In Figs. 6 and 6 is illustrated a plotting device for arrangementsaccording to Figs. 4 and 5. On two pairs of rails 120, 121 and 122, 123only 122 of which is fully drawn, there run two narrow extended frames124 and 125 across one another. In their particular crossing point thereruns in rollers (see also Fig. 6 126 and 127 a carrier 128 for theindicating member. This carrier can be designed as a pointer, as a lampwith projector or in any suitable manner. In Fig. 6 is shown a lampprojecting a sharp light beam, in Fig. 6 a piece of a pointer arm. Aboveor below the device is arranged a transparent or opaque (depending uponwhether a pointer or a light beam is used) plate 129 with theorientation division 130 (indicated by broken lines). It may becarriedout as the projection of a. sphere division into longitudinal andlatitudinal circles, or in meridians, or as a hemisphere with originaldivision. The frames are connected through cords 131, 132, 133, 134,with the turning knobs 135 and 136 of the double compensator 137 for thetwo linear groups and, on turning these knobs, the frames are positivelymoved. It is immediately clear that the two frames must be connectedwith the contact device of the artificial line compensator in such away, or the latter must be so arranged, that the crossing point of theframes keeps the particula P011113 0f p j tion of the point ofintersection of the two cone base circles on the horizontal plane ofFig. 5. In case of a hemispherical transparent or translucentorientation chart, the point at. which the light strikes the chartcorresponds to the exact location of the space vector, which is thepoint of intersection of the aforementioned cone base circles, or, incase of a plane orientation chart, as shown in Fig. 6, to its point ofprojection.

Fig. 6 shows, in the simplest form, the circuit of aninstallation'according to Figs. 4, 5 and 6, and substantially on theprinciple disclosed in the aforementioned application. For each lineargroup of devices, only three receivers 161, 162, 163 and 164, 165, 166respectively are assumed. The centre receiver can be common for bothgroups but is illustrated here as a double receiver, (one in full, theother in dotted line) in order not to complicate the clearness of theillustration. Each group of receivers is connected with a changeoverswitch 167 and 168 which allows of changing-over the receiverconnections with the compensator. This changing over has the purpose ofcompletely utilizing the compensator for the angles 0 to 90 and 90 to180, that is, to manage with half the length of the artificial lines inthe compensator. It is desirable, however, to dimension the com pensatorsomewhat greater in order that it need not be reversed just at the apex.The outermost receiver of each group (in the illustrated example 163 and166) is directly connected, and every other one is connected through itscontact slide in the compensator to the primary coil of its respectivetransformer 171, 172, 173 or 174, 175, 176. The secondary coils of thesetransformers are all connected in series and through the amplifier 169to thetelephone 170. The chain of the compensator is divided into equalsteps and connected to the circular rows of contacts 177, 178 or 179,180 of the compensators in such a way that between successive contacts,in the sequence of the receivers in the linear receiver groups 5 and 6,Fig. 4, the second receiver in each case is switched forward by theamount of one chain section of the compensator line and the thirdreceiver in each case by the amount of two sections, and so on. Witheach contact row isassociated a circular contact rail 181, 182 and 183,184 respectively which is connected with the corresponding transformer.The connection between each contact row and its rail is effected bybrushes 185, 186 and 187, 188 respectively, which are carried by arotatable contact arm. Connected to the contact arm is the elementcoupling which serves for actuating the indicating mechanism,aforedescribed with reference to Fig. 6, andwhich is represented in theconstructional example by the cords 189, 190.

If an artificial line of the double compensator of Fig. 6 is to be usedseparately for a vertical linear group, such as 7 in Fig. 4, for moreaccurate re-determination of the elevation, this can be accomplished bymeans of the two switches 191 and 192, the first of which effects thereversal to the vertical linear group of receivers, of which at switch191 only short leads from the contact points are shown whilst the second192 disconnects the transformers of the right hand side and changes theconnection to the amplifier. The reading of the height is then done on aparticular height scale 193.

In Fig. 7 an arrangement, in principle similar to Fig. 6, isdiagrammatically illustrated. Instead of the linear frames 124, 125 ofFig. 6 spherical shell portions or frames 140, 141 are used, one withinthe other and. provided with peripheral slits 142, 143 respectively,

- electric waves.

which cross each other at right angles. The frames are pivotedrespectively on crossed axles 144, 145. Axle 144 lies within the innerspherical shell or frame, while axle 145, mounted in the frame 146,consists of two alined but separated parts, in order to accommodate theinner shell 140. In the common center of the spherical shells or framesis mounted a ball and socket joint 147, carrying an arm 148, whichsimilarly as described with reference to Fi 6, runs in rollers at thepoints where it passes through slits 142 and 143. It may be designed asa pointer or a carrier of a lamp with a point beam projector. In thepresent case it is assumed to carry a lamp throwing a point beam.

For orientation purposes is used a transparent or a translucentspherical envelope divided into longitudinal and latitudinal degrces, orit may be divided into meridians or into greatest sphere circles. Themovement of the beam is effected again by the contact operating deviceof the compensator lines, for instance. by cords 150, 151 through theturning knobs 153, 152 respectively of the compensator 154.

Arrangements of the described type can be employed equallyadvantageously for the transmission and reception of wave energy of anykind, for instance, sound waves and In the latter case, the mechanicaloscillators are to be replaced by electrical oscillators, preferably bythose characteristic. Arrangements of the described type with soundreceivers serve, with particular advantage on flying fields for loeatingaircraft.

The illustrated general forms are, of course, only examples of themanner in which our invention may be reduced to practice, and should notimply a limitation of the group combinations or the construction of thecompensation or the indicating devices. With respect to the grouping ofthe receivers the main feature is that always a plurality of groups isused, whose individual characteristics as geometrical loci fordifi'erent planes are so combined, that one single valued resultinggeometrical locus for the sought object obtained. The indicatingdevices, of course, can also be designed to make records instead ofgiving momentary visible indicacations as shown. The construction of thetransmitters or receivers is not of importance in carrying out the ideaof the invention, so long as care is taken that these apparatus work astrue as possible with respect to phase and amplitude, that is, withoutdistortion.

We claim 1. Arrangement for directional transmission and reception ofwave energy in any desired direction in space, comprising at least twogroups of oscillators arranged with their eifective directive ranges indifferent planes crossing each other, an independent compensation meansfor each group adapted to vary the directional character of its groupwithin its range, to obtain maximum wave energy effects-in the desireddirection, and means for combining the resultant maximum directionaleffects of the two groups to obtain a definite single valued maximumdirective wave energy effect in space.

2. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising at least two similargroups of oscillators arranged with their effective directive ranges indifferent planes crossing each other at right angles, an independentcompensation means for each group adapted to vary the directionalcharacter of its group within its range, to obtain maximum wave energyeffects in the desired direction, and means for combining the resultantmaximum directional effects of the two groups to obtain a definitesingle valued maximum directive wave energy effect in space.

3. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising in com bination twosimilar linear groups of oscillators positioned in one plane andcrossing one an other at right angles, an independent compensator foreach group, adapted to vary the which themselves have no naturaldirectionaldirectional character of its group within the directive rangeof the group to obtain maximum wave energy effects in the desireddirections, and means for combining thcresultant 5 maximum directionaleffects of the two groups to obtain a definite single valued maximumdirective wave energy effect in space.

4. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising in combination two similarlinear groups of oscillators positioned in one plane and crossing oneanother at right angles, and a third similar linear oscillator grouparranged in the crossing point of and at right angles to the two firstnamed groups, an independent compensator for each group adapted to varythe directional character of its group within the directive range of thegroup to obtain maximum wave energy effects in the desired directions,and means for combining the resultant maximum directional effects of twogroups to obtain a definite single valued maximum directive wave energyeffect in space.

5. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising in combination two similarlinear groups of oscillators positioned in one plane and crossing oneanother at right angles, and a third similar linear oscillator group,arranged in the crossing point of, and at right angles to the two firstnamed groups, an electrical compensator for each of two groups,comprising an artificial line adapted to vary the directional effect ofits group within the directional range of the group to obtain maximumwave energy effects in the desired directions, a switching device forswitching one of said of oscillators, and means for combining theresultant maximum directional effects of the chosen two of said threegroups to obtain a definite single valued maximum wave energy effect inspace.

6. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising at least two groups ofoscillators arranged with their effective directive ranges in differentplanes crossing each other, an independent compensation means for eachgroup, comprising an artificial line, adapted to vary the directionalcharacter of its group within its range, to obtain maximum wave energyeffects in the desired directions. and an indicator connected to all ofsaid artificial lines for indicating the combined directional efiects ofthe two groups to obtain a definite single valued directive indicationin space.

7. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising at least two groups ofoscillators arranged with their efiective directive ranges in differentplanes compensators over to the third linear group" crossing each other,an independent compen-' dicating device on which chart the spacedirection of said single valued maximum effect is indicated by saidvlsual indicator.

8. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising at least two groups ofoscillators arranged with their effective directive ranges in differentplanes crossing each other, an independent compensation means for eachgroup, comprising an artificial line and an adjusting device for varyingsaid line, to vary the directional character of the pertainingoscillator group within its range to obtain a maximum wave energy effectin the desired directions, an indicator connected simultaneously to allof said artificial lines for indicating the combined directional effectsas a single valued maximum, a guiding device for each of said adjustingdevices mechanically coupled to it, a visual indicating device havingmeans for projecting a point light beam, and being guided by both ofsaid guiding devices, and a transparent orientation chart located withinthe operating range of said light beam and on which the latter indicatesthe space direction of said single valued maximum effect.

9. Arrangement for directional transmission and reception of wave energyin any desired direction in space, comprising at least two groups ofoscillators arranged with their effective directive ranges in differentplanes crossing each other, an independent compensation means for eachgroup, comprising an artificial line and an adjusting device for varyingsaid line, to vary the directional character of the pertainingoscillator group within its range to obtain a maximum wave energy effectin the desired directions, an indicator connected simultaneously to allof said artificial lines for indicating the combined directional effectsas a single valued maximum, a guiding device for each of said adjustingdevices mechanically coupled to it, a visual indicating device havingmeans for projecting a, point light beam, and being guided by both ofsaid guidingdevices, and a hemispherical transparent orientation chartlocated within the operating range of said light beam and on which thelatter indicates the space direction of said single valued maximumeffect.

10. Arrangement for directional transmission and reception of waveenergy in any desired direction in space, comprlsing at least two groupsof oscillators arranged with their effective directive ranges indifferent planes crossing each other, an independent compensation meansfor each group, comprising an artificial line and an adjusting devicefor varying said line, to vary the directional character of thepertaining oscillator group within its range to obtain a maximum waveenergy effect in the desired directions, mindicator connectedsimultaneously to all of said artificial lines for indicating thecombined directional effects as a single valued maximum, an elongatedguide frame for and coupled to each of said adjusting devices, and

go movable by its pertaining adjusting device transversely to its axis,said two frames being arranged at right angles to one another, a visualindicating device guided by both guide frames, and an orientation chartcooperatively associated with said visual indicating device on whichchart the space direction of said single valued maximum eflfect isindicated by said visual indicator.

In testimony whereof we alfix our signa- 30 tures.

HEINRICH HEGHT. WILHELM RUDOLPH.

